But so few people have actually seen the app that there's been frustratingly little written on what it's actually like to use.

TechRadar wanted to go deeper, so we wangled a few hours to play with it. We've held it in our very own hands. And we love it.

Going mobile has been a massive push for the music-streaming service, as exclusively revealed to TechRadar earlier this year, while a US launch isn't that far off. It's not being outrageous to suggest that taking Spotify onto mobile is make or break for the company and as such Spotify says it has been careful to follow Apple's app submission guidelines.

First of all, a heads-up. This app has only just been submitted to Apple, so this isn't a final review, just a full hands-on, first impressions piece. The app is in beta and so isn't finished - we've heard that Spotify may further improve the graphics, as well as speed up playlist synching (not that it seems particularly slow).

This is a really interesting time to see the Spotify iPhone app, especially as there has been much speculation over whether Apple will accept it into the App Store. Is it too close to stepping on the toes of iTunes? Or will Apple simply view it in the same way as Last.fm, which it waved through without issue?

The headline feature of Spotify for iPhone is the ability to save playlists for offline playback, and it's this which might cause Apple most concern (though as you'll hear, this needs Wi-Fi). It will, however, assuage the concerns of those who continue to disparage the network coverage of O2, AT&T and others.

You'll need a Spotify Premium account to use the iPhone app, which may seem draconian, but someone needs to pay for all this stuff.

Like the Last.fm app, Spotify for iPhone also means you can listen to music over-the-air via Wi-Fi or 3G but naturally Spotify's ability to search and stream any track in its library is absolutely key. The Radio function isn't present in the Spotify iPhone app like it is on the desktop, while there's also no Play Queue or way to save previous searches.

Unlike the iPod app that can run in the background, Spotify on iPhone suffers the same problem that Last.fm has - it's only single-tasking and so when you're listening to tunes, the rest of your iPhone is dead to you.

Despite the early stage of the software, the Spotify app is fast and responsive and, like the desktop software, streams tracks within seconds. Early software on the iPhone has a habit of crashing, and indeed this did once.

So let's get on with it. Spotify on iPhone. As soon as we logged into the app, we were presented with a list of playlists – there are three main tabs, Playlists, Search and More and we'll separate our hands-on into those three areas.